Hi I have this project to do about crosses and I can't think of what the answer is for the following questions: What is the area rule of the crosses (the table below will help you)?
I also need to know what the formula is for it?
Please help me Hi Joel, I wish I could see a diagram I don't know where the numbers come from and what the cross looks like. I approached this with differences.
If I have 3 consecutive terms in the first row _{n-1}, a_{n}, a_{n+1}
then the two numbers in the row directly below these 3 are _{n} - a_{n-1}, a_{n+1} - a_{n}
Taking differences a second time, the number below these 2 in the third row is _{n+1} - a_{n}) - (a_{n} - a_{n-1})
But all the numbers in the third row are 4 and henve _{n+1} - a_{n}) - (a_{n} - a_{n-1}) = 4
and hence _{n+1} = 2 a_{n} - a_{n-1} + 4
Thus if you know the first two terms are a _{1} = 5 and a_{2} = 13 you can generate the rest. For example_{3} = 2 a_{2} - a_{1} + 4 = 2 13 - 5 + 4 = 25
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